Sorry for elaborating so much. It was just so obvious in this case. It is good to be careful, and very worrying how much this interpreter triggers. And some game engines in general.
But yeah, the game itself lags af. It is 20 years old tech. That means single threaded and limited memory usage. I could pamper the game with literally a hundred times it's current memory usage. And about 10+ times the cpu load. If you do certain things it even locks up sometimes for a few seconds.
A freshly loaded save games and doing nothing: the game takes up 0% cpu and 113MB. And I need about 2-3 seconds to go from room to room, while the single core it uses barely gets used to 50%. This normal?